Axiom Home Page Forums General Discussion Advice from Axiom Owners M22/Rava setup starting point?

Thanks for the tips! I have a few idiotically basic follow-up questions, if you'll indulge me:

1) Does setting mains in the Denon 1802 to "small" and turning the sub crossover all the way up have the same effect as setting the mains to "large" and using the sub to set the crossover at 80 Hz?

2) Would setting the mains to "small" make it impossible for me to set the crossover below 80 Hz?

3) What is "phase"?

4) If I had an SPL meter, what exactly would I do with it?

Sorry to be so clueless, but they didn't teach me this stuff in grad school! (Relax... I'm not an engineer!)